1. Field of the Invention
The present invention is generally related to a marine propulsion engine with a catalyst and, more particularly, to an engine in which a catalyst is contained within a cavity and retained in position between the engine block and the engine head.
2. Description of the Prior Art
It is well known to those skilled in the art of engine design that various types of catalysts can be beneficial in reducing exhaust emissions emanating from the engine. Those skilled in the art are also familiar with many types of configurations in which catalysts are used in conjunction with engines of marine propulsion systems.
U.S. Pat. No. 6,660,235, which issued to Holpp et al. on Dec. 9, 2003, describes a catalyst carrier configuration for installation close to an engine. The configuration includes a housing and at least one catalyst carrier body disposed in the housing. The body has partition walls defining a plurality of passages for an exhaust gas. A flange surrounds the catalyst carrier body and extends radially outwards from the catalyst carrier body.
British Patent GB 2 231 283, which was filed on Apr. 5, 1990, describes an exhaust gas cleaning device that is constructed of a honeycomb core body defining a number of network-patterned axial gas flow passages. Around the central axis of the honeycomb core body, there is also defined a cylindrical hollow space of an outer diameter satisfying a particular formula.
U.S. Pat. No. 5,413,767, which issued to Breuer et al. on May 9, 1995, describes a mechanically stabilized heating catalyst configuration. The apparatus includes first and second honeycomb bodies through which a fluid can flow in succession. At least one of the honeycomb bodies is heatable and the honeycomb bodies each have a multiplicity of channels formed therein defining channel walls.
German disclosure document DE 40 38 169, which was filed on Nov. 30, 1990 by Christl et al., describes an internal combustion engine with a motor housing consisting of a cylinder head in a crankcase. The arrangement comprises an exhaust port system located in the motor housing to convey the exhaust gases from the combustion chamber to an exhaust line system. It has an exhaust filtering element, or catalytic converter, which is located in the path of the exhaust gas. In order to maintain the temperature level required for proper operation of the exhaust filtering element located in the path of the exhaust gas without additional is measures, it is proposed that the exhaust gas filtering element be located in the motor housing and within the exhaust port system.
U.S. Pat. No. 5,916,135, which issued to Yoshida et al. on Jun. 29, 1999, describes an engine exhaust emission control system for an outboard engine system. The system is intended for use with a four cycle outboard engine. The engine comprises a mounting member, an engine block mounted on the mounting member, an extension housing coupled to the mounting member and extending downward therefrom, and an engine oil pan mounted under the mounting member within the extension housing. The engine exhaust emission control system comprises a catalyst assembly positioned in the exhaust gas expansion chamber, the catalyst assembly having a catalyst case aligned with the oil pan in the lengthwise direction thereof.
U.S. Pat. No. 4,900,282, which issued to Takahashi et al. on Feb. 13, 1990, describes an exhaust gas purifying device for a marine engine. The catalyzer material is supported by a heat conductive bracket and the bracket is cooled by a cooling jacket that is supplied with coolant from the engine cooling jacket. In one embodiment, the water jacket is cooled both internally and externally by delivering water from the cooling jacket into the exhaust system to impinge upon a wall of the cooling jacket.
U.S. Pat. No. 5,203,167, which issued to Lassanske et al. on Apr. 20, 1993, describes a marine propulsion device internal combustion engine. An exhaust catalyst apparatus is mounted on the cylinder block and includes a tongue extending into the cylinder block exhaust passage and dividing the cylinder block exhaust passage into an upstream portion communicating with the exhaust port and a downstream portion communicating with the exhaust outlet. The apparatus includes an exhaust passage communicating between the upstream portion and the downstream portion and a catalyst is located in the apparatus exhaust passage.
U.S. Pat. No. 5,239,825, which issued to Shibata on Aug. 31, 1993, describes an exhaust emission control device for an outboard motor. A catalyst material holding structure is mounted within an exhaust passage of an engine. A thermally insulating interstice is located between an inner wall of the exhaust passage and the outer periphery of the catalyst material holding structure, so that the interstice physically separates the catalyst material holding structure from the inner wall of the exhaust passage.
U.S. Pat. No. 6,662,555, which issued to Ishii on Dec. 16, 2003, describes a catalyzer arrangement for an engine. The arrangement includes an improved construction that does not require a large space for furnishing a relatively large volume catalyzer. The engine is surrounded by a protective cowling. A cylinder body of the engine has a plurality of cylinder bores spaced apart from each other. At least one catalyzer is disposed in the exhaust passage of the engine.
U.S. Pat. Re. 36,888, which issued to Sougawa et al. on Oct. 3, 2000, describes an exhaust gas purifying device for an outboard motor. At least one exhaust port is provided which opens into a first exhaust passage having a first catalyst member lining at least a portion of its inner wall. The first exhaust passage then opens into an exhaust expansion chamber. Next, a second exhaust passage originates just beyond the expansion chamber. A second catalyst member is mounted within and across a section of exhaust passage beyond the first exhaust passage and at a location above the water line within which the outboard motor operates.
U.S. Pat. No. 5,546,748, which issued to Iwai et al. on Aug. 20, 1996, describes an exhaust system for an outboard motor. A number of embodiments of exhaust systems for outboard motors including a combined is catalyst bed and exhaust manifold forming member affixed within the cylinder block of the engine so as to be readily detachable for servicing. This combined member is provided with a separate cooling jacket for its cooling.
U.S. Pat. No. 5,490,382, which issued to Kato on Feb. 13, 1996, describes a catalyzer support system for exhaust cleaning of an outboard motor. A catalytic exhaust treatment system for an outboard motor is described wherein a catalyst bed is supported within the exhaust pipe on a support plate that permits the catalyst bed to expand and contract relative to the surrounding exhaust pipe from which it is spaced. The exhaust gases can flow through the catalyst bed and around the catalyst bed for complete treatment.
U.S. Pat. No. 5,822,985, which issued to Yoshimura on Oct. 20, 1998, describes an exhaust passage structure of an outboard motor. The structure is provided for an outboard motor unit having an engine holder mounted to a hull through a bracket, an engine disposed to an upper portion of the engine holder, a driveshaft housing disposed to a lower portion of the engine holder and an exhaust passage structure extending from the engine into water through the driveshaft housing. An opening is provided and opened at a position between the location of the bracket, preferably the catalyst disposed in the first exhaust expansion chamber, and an upper end of the engine cylinder so that the water does not enter the second exhaust expansion chamber even if a draft line of the water rises.
U.S. Pat. No. 5,855,495, which issued to Kubo on Jan. 5, 1999, describes an exhaust gas cleaning device of an outboard motor unit. A catalyst is disposed below the engine and inside a space having substantially a triangle shape, in a plan view, defined by a central line of one of the cylinder rows, a central line of another one of the cylinder rows and a central line of the expansion exhaust chamber.
U.S. Pat. No. 5,439,651, which issued to Kato on Aug. 8, 1995, describes a catalyzer support system for exhaust cleaning of an outboard motor. A catalyst exhaust treatment system for an outboard motor is described wherein a catalyst bed is supported within the exhaust pipe of a support plate that permits the catalyst bed to expand and contract relative to the surrounding exhaust pipe from which it is spaced. The exhaust gases can flow through the catalyst bed and around the catalyst bed for complete treatment.
U.S. Pat. No. 5,378,180, which issued to Nakayama et al. on Jan. 3, 1995, describes an exhaust system for an outboard motor. Two embodiments of outboard motors embodying tuned exhaust systems having exhaust pipes and expansion chambers into which the exhaust pipes extend are described. A catalyst is positioned in the exhaust system downstream of the point where the exhaust pipe terminates in the expansion chamber so as to preclude interference with the exhaust tuning. The catalyst bed is removable for ease of servicing without necessitating removal of the outboard from its attachment to the associated watercraft and a trap device is provided for precluding water from entering the engine through its exhaust ports.
U.S. Pat. No. 5,346,417, which issued to Isogawa on Sep. 13, 1994, describes an exhaust gas cleaning device for an outboard motor. An expansion chamber is formed in the driveshaft housing and the exhaust gases are delivered to the expansion chamber from an exhaust pipe that extends at least in part through the expansion chamber and which terminates at its lower end in the lower portion of the expansion chamber. A catalyst bed is positioned at the upper end of the expansion chamber and beneath the engine and through which the exhaust gases must pass for discharge through a further exhaust conduit which extends at least in part through the expansion chamber and which terminates at an underwater exhaust gas discharge.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
It would be significantly beneficial if a simple, but rugged, arrangement for containing a catalyst member in association with an exhaust stream could be provided. It would be particularly beneficial if the arrangement for attachment could be compact, require little or no extra space for the catalyst member, and securely contain the catalyst member in an appropriate position relative to the stream of exhaust gas emanating from the engine.